This invention relates to pulse detonation systems, and more particularly, rotary air valve firing patterns for resonance detuning.
With the recent development of pulse detonation combustors (PDCs) and engines (PDEs), various efforts have been underway to use PDC/Es in practical applications, such as in aircraft engines and/or as means to generate additional thrust/propulsion. It is noted that the following discussion will be directed to “pulse detonation combustors” (i.e. PDCs). However, the use of this term is intended to include pulse detonation engines, and the like.
Because of the recent development of PDCs and an increased interest in finding practical applications and uses for these devices, there is an increasing interest in implementing PDCs in commercially and operationally viable platforms. Further, there is an increased interest in using multiple PDCs in a single engine or platform so as to increase the overall operational performance. However, because of the nature of their operation, the practical use of multiple PDCs is often limited by some of the operational issues they present, particularly on downstream components. That is, current implementations using multiple PDCs fire (or detonate) the PDCs in a sequential firing pattern.
For example, if a plurality of PDCs are arranged in a circular pattern, they are fired sequentially in a clockwise direction. However, the sequential firing of PDCs can be disadvantageous for a number of reasons.
Specifically, the sequential firing of multiple PDCs can result in creating resonance in downstream components of an engine. The creation of this resonance can result in high cycle fatigue failure in downstream components. Additionally, when one off-axis PDC tube is fired at a time this can create large flow asymmetries can lead to losses downstream as the flow passes through nozzles, etc. Additionally, force loading on downstream components can be asymmetric, thus requiring additional structure and weight to compensate for this loading.
Therefore, there exists a need for an improved method of firing PDCs so that any resonant frequencies are detuned.